1. Field of the Invention
The present invention relates to a connector configured such that metal terminals (which may hereinafter be referred to merely as “terminals”) connected to end portions of lead wires are assembled to a connector housing made of, for example, resin, as well as to a circuit-board-mounting case, or casing, to which the connector is attached.
2. Description of Related Art
Japanese Patent Application Laid-Open (kokai) No. H10-247541, and Japanese Patent Application Laid-Open (kokai) No. 2004-362814 disclose, for example: a terminal being press-fit into a press-fit hole of a connector housing made of resin to thereby be assembled to the connector housing; and the terminal being in a locked condition against detachment.
Each of such terminals is formed from a flat sheet of metal, such as sheet metal, and comprises a predetermined, elongated narrow flat sheet. The terminal is longitudinally press-fit into the press-fit hole of the connector housing, thereby being assembled to the connector housing. When such a metal terminal is press-fit into the press-fit hole, a stopper portion of the metal terminal butts against a stopper portion, or butting face, of the press-fit hole, thereby positioning the metal terminal with respect to a press-fit direction (i.e., a direction in which press-fitting progresses). In order to provide detachment prevention means for preventing detachment of the metal terminal in a direction opposite the press-fit direction (i.e., the direction toward the inlet of the press-fit hole), side edge portions of the metal terminal have respective projections, or biting portions, which bite into the wall surface of the press-fit hole following the press-fitting of the metal terminal into the press-fit hole. The projections biting into the wall surface of the press-fit hole prevents detachment of the metal terminal from the connector housing.
In such a connector, a metal terminal may be assembled to a connector housing in the following manner: 1) the metal terminal is connected to an end portion of a lead wire, or a conductor, by crimping or a similar process; and 2) the metal terminal is press-fit into a press-fit hole of a connector housing from a lead-wire connection portion located on the front end side with respect to a press-fit direction, by pushing a counterpart connection portion located on the rear end side thereof with respect to the press-fit direction, to thereby be assembled to the connector housing. More specifically, the lead wire is inserted through the press-fit hole of the connector housing from the exterior side of the connector housing. Then the metal terminal is connected to an end portion of the lead wire. Then the lead wire is pulled in a direction opposite the direction in which the lead wire was inserted (i.e., the lead wire is pulled toward the exterior of the connector housing), thereby press-fitting, or pressing, the metal terminal into the press-fit hole and thus assembling the metal terminal to the connector housing.
When the above-mentioned metal terminal is press-fit into the press-fit hole of the connector housing, even when the metal terminal undergoes press-fitting in such a manner as to be pressed straight along the press-fitting direction, the metal terminal is likely to be deformed. More specifically, the metal terminal is likely to be flexed, folded or buckled in its plane direction due to: a) the cross-sectional shape of the metal terminal; b) the press-fit resistance caused by friction between the metal terminal and the wall surface of the press-fit hole; or c) a deviated load. Such deformation is likely to arise particularly when, in the course of press-fitting, the projections of the side edge portions of the metal terminal encounter high resistance with the wall surface of the press-fit hole.
In the above-described connector, a watertight seal can be provided for the interior of the press-fit hole. In one method, in molding the connector housing, such as from resin, the metal terminal can be placed in a mold as an insert and insert-molded to thereby be integrated with the connector housing. However, this method is accompanied by complication of the mold and a molding process, resulting in an increase in cost. Therefore, the following alternate method is conventionally employed: 1) the connector housing is manufactured in a separate process; 2) a sealing elastic member, or seal packing, formed of an elastic material, such as rubber, is externally attached to an end portion of a lead wire located toward the metal terminal, or to a portion of the lead wire located toward the end portion; and 3) the sealing elastic member, together with the metal terminal, is subjected to press-fitting work. By this alternate method, a seal is established between the outer circumferential surface of the lead wire and the wall surface of the press-fit hole.
In the case where the connector having such a watertight seal employs the aforementioned alternate method of assembling the metal terminal to the connector housing, the press-fit resistance of the sealing elastic member is added to the press-fit resistance of the metal terminal. Thus, the overall press-fit resistance increases. When the metal terminal, together with the sealing elastic member, is press-fit into the press-fit hole by pressing its counterpart connection portion located on the rear end side, the force to be applied for press-fitting (i.e., the press-in force) must be further increased. Therefore, the aforementioned deformation, such as flexure, folding or buckling of the metal terminal is more likely to occur.
Additionally, even when the metal terminal can be press-fit without deformation, after press-fitting, an external force applied in a plane direction to a projecting end of the metal terminal is likely to cause the metal terminal to be readily flexed since metal terminal is low in section modulus with respect to a plane direction. Also, such a metal terminal may vibrate or move upon being subjected to vibration or an external force. In the case where the counterpart connection portion of the metal terminal is connected by soldering to an electrode terminal of the circuit board, such vibration or movement of the metal terminal may cause an electrical disconnection or cracking in the solder connection.
As discussed above, the conventional connector is low in positional stability of the metal terminal. Thus, the press-fitting of the metal terminal into the press-fit hole thereby involves the risk of occurrence of the above-mentioned problems.